The present invention relates generally to semiconductor packages and, more particularly, to an improvement in the feed leads of a semiconductor package.
A conventional semiconductor package is shown in FIG. 3. A semiconductor chip 1 is secured with a solder 2. Gold wires 5 connect signal leads 3 and a feed lead 4 to the semiconductor chip 1. Plating 6 is provided to give reliable connections between the gold wires 5 and the leads 3 and 4. A seal material 7 is provided to form a package.
In FIG. 4, a layout of pads mounted on a board consists of six pairs of signal pads 8 and a pair of feed pads 9. The semiconductor chip 1 has an integrated circuit and is supplied with power via the feed leads 4 and the gold wires 5. In order to minimize the resistance and thus the voltage drop due to the resistance, the width of the feed leads 4 is made wider than that of the signal leads 3. The width of the feed leads 4, however, is limited in order to prevent the formation of a gap between the feed leads 4 and the seal material 7 because of a difference in thermal expansion between them.
However, in the above semiconductor package, the feed leads are made wide over the entire length from the end secured to the substrate to the end mounted on the board. Consequently, a gap is produced between the seal material and the feed leads because of a difference in the thermal expansion. In addition, the feed pads must be wider than the signal pads so that two types of pads must be designed.